Studies are proposed to evaluate the pharmacologic actions and interactions of the hypothermia producing neuropeptides, beta-endorphin, neurotensin and bombesin and the hyperthermia producing neuropeptides TRF, somatostatin, and somatostatin analogs. Further studies will be carried out to determine the relationship of the actions of these peptides to the actions of the monoamine brain neurotransmitters to affect thermoregulation. Development of peptide antagonists or active or passive immunization methods to inhibit the CNS effects of endogenous beta-endorphin, neurotensin, bombesin, TRF and somatostatin may allow demonstration of physiologic roles of these peptides to control thermoregulation. Other studies will be directed at determination of the CNS sites of action of these peptides by placing small quantities of peptide or their antagonists into discrete brain regions. Efforts to characterize mammalian bombesin will continue. Once the structure of mammalian bombesin is known, new antibodies will be raised and the distribution of this peptide in mammalian tissues will be determined using radioimmunoassay and immunocytochemical methods. We will also study the plasma and brain levels of these peptides in hibernating animals. These various studies add fundamental information to thermoregulation pharmacology and physiology and also provide a relevant method to assess the neurobiology of peptides.